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WILLIAM H. HOBBS 



4, The intermediate and outer groups of arcs of the imperfectly 

 concentric series are of later date and consist of festoons, or spring 

 from a number of cuspate areas. This arrangement is described 

 as "linking" or "syntaxis." 



Pre-Cambrian Arcs 

 Paleozoic Arcs 

 Mesozoic Arcs 

 Volcanoes 



Fig. 2. — Sketch map of Asia to bring out the plan of the principal mountain 

 ranges with indications of the partially submerged chains. 



5. Several arcs of different radii in some cases spring from the 

 same pair of linking areas which thus become centers of " virgation." 

 The nearly parallel ranges near where they are linked are sometimes 

 referred to as coulisses (Fig. 3). 



